PRRS-Resistant Pigs Developed Through Gene Editing

Porcine reproductive and respiratory syndrome (PRRS) virus has been terrorizing the pork industry for over 25 years, but the end may be in sight. Researchers and scientists from the University of Missouri, Kansas State University, and Genus pIc bred pigs that are not affected by PRRS.

A protein called CD163 was found to be the vessel that spread PRRS in pigs. Scientists edited the gene that makes CD163 to prevent pigs from being susceptible to the virus. The litter of pigs that was born without the protein was exposed to the virus and remained healthy, continued to grow, and had no PRRS symptoms. Gene editing stopped the virus from spreading, and the pigs without the protein saw no developmental changes.

“I’m overwhelmed at how night-and-day this virus is affecting the animals,” said Dr. Randall Prather, a professor of animal sciences at the University of Missouri who has helped lead the project. “These pigs are running around the pen like nothing happened.”

In the past, researchers thought a protein called sialoadhesin was thought to be the driving force behind the spread of PRRS, but when sialoadhesin was removed, pigs were still just as vulnerable to the virus.

“We need to see how these animals perform in a production setting. Right now they appear to grow at the same rate and appear to be normal pigs,” said Prather. “We have animals on second farrowing now.”

Genus pIc has the exclusive global license for the PRRS-resistant pigs. If everything continues successfully throughout development, the company will move forward with necessary approvals and government registrations.

Prather stresses that farmers shouldn’t be looking for this technology to reach them in the very near future, but these CD163-free pigs are looking incredibly promising.

PRRS costs North American pork producers more than $660 million annually, and no vaccine has proved effective at preventing the virus. Millions of pigs and piglets are affected by the PRRS virus each year.

“PRRS not only costs producers economically, but it costs them emotionally, too,” said Prather. “I think pork producers will be excited.”